miller



Feb. 10,v 1931.- F. E. MILLER 1,791,932

' ELECTRICAL STETHOSCOPE Filed Feb. 24, 192s llilll Ill lllill i www INVENTOR ATTORNEY 50 stages.

Patented Feb. 10, 1931 UNITED STATES FRANK E. MILLER, F NEW YORK, N'.l Y.

ELECTRICAL smn'rnoscorn Application led February 24, 1928. Serial No. 256,658.

.It is an object of my invention to design an electrical stethoscope having a transmitting device so constructed that it will be easily and readily adapted tothe portions of the human body from which I desire to obtain registration. It is also my purpose to design a stethoscope of this type which will give me a visible oscillograph record of the sounds received and at the same time make it possible to out out and eliminate from my visible reproduction all extraneous noises from the body either internal or external.

My invention will be -more readily under stood by reference to the attached drawing in which like figures refer to like parts.

Fig. l shows my preferred transmitting device in section elevation.

Fig. 2 shows a diagram of 1the hook up diagrammatically.

Referring particularly to Fig. 1, it will be seen vthat my preferred transmitting member consists of a permanent iron magnetic member D, non-magnetic case E, a threaded portion F which sets into the screw cap O containing the magnetic vibrating unit G actuated by the electromagnet Q. This drawing also shows the soft rubber securing ccnductor unit M, having integral therewith the suction resonating chamber L. The chamber L is constructed after the same shape of the tympanum of the ear to respond more readily y to the impressed sounds and transmitted through the hollow interior of M to the diaphragm Gr andthe electromagnet, the shape l of M being adapted most readily to come in contact withy the portions of the Abody being examined.l Referring to Fig. 2 my preferred transmittingunit is electrically connected to the input side of an audio amplier AA of any conventional type. I refer to use, however, the type known as doubleimpedance coupling. 'Ilhe output side of this amplifier lis then connected to a specifically constructed electric frequency filter consisting ofthe proper arrangement of choke coils, that is of inductances, resistances and capacities, and

the output of which is connected to a conventional type of visible oscillograph containing the necessary amount of amplifying tion, what I claim and desire to secure by United States Letters Patent is:

1. In an electrical stethoscope an electro-l magnetic sound transmitting unit consisting of an electromagnet, a diaphragm free to vibrate, a short, flexible, hollow rubber sound conducting portion having an eccentric protruding cavity resembling the tympanum of the human ear adapted to make contact with the human body, in combination with van audio, amplifier and a frequency filter anda visible oscillograph.

2. In an electrical stethoscope'an electromagnetic sound transmitting unit consisting of an electromagnet, a diaphragm free to vibrate7 a short, iiexible, hollow rubber sound conducting portion having an eccentric protruding cavity resembling the tympanum of the human ear adapted to-make contact With the human body, in combination with an electric sound frequency filter adapted to preclude the passing of sound waves of any 4predetermined frequencies internal or external to the human body.

In witness whereof I have hereunto set my hand to this specification this 21st day of February, 1928.`

FRANK E. MILLER, M. D.

Having thus described my inven- 

